Linux and the TV
About eight years ago, everybody was talking about the
convergence of technology. Computers had just gained the status
of "Multimedia" machines. One could watch full motion,
high-resolution videos in tiny 320x200 windows played off a
massive 650mb cdrom disc and listen to exciting FM quality music
from tinny 8 bit cards. And then someone realized that every
device on earth could be integrated into the computer. One can
now find integrated 3d video cards, audio cards, mpeg decoders,
internal modems, web cams, pluggable microwave (huh?), and most
importantly, TV Tuner Cards.
TV Tuner cards have existed for quite some time. Today one can
pickup a TV tuner card for less than $50 or even find it
integrated in the 3D/2D video card. Before you throw your TV set
off the terrace, it would be worth contemplating the fact that
most TV Tuner cards can hardly match the quality of any decent TV
set. Unlike TV sets, which run on an analog system and do not
rely on image precision, computer CRTs have to display images
with a lot more detail. In most cases due to the low resolution
of broadcasts, the computer CRT cannot display a sharp image.
Computer CRTs display colors, relatively less sharply and
vibrantly compared to TV sets.
A TV Tuner card has three important components. The tuner chip is
used to "listen" to a specific broadcast frequency. Most cards
have major problems tuning weak signals, especially when an
antenna is the input source. A video decoder chip processes the
incoming signal and processes the broadcast format
(PAL/NTSC/SECAM) and pushes it to an overlay area of the main
video card. The overlay area is a part of the video memory which
is directly written onto by the TV tuner to display the TV
channel. Finally a sound decoder chip, processes the audio
signals and can additionally decode Stereo/Dolby signals before
feeding it to the speakers.
If you do however have the money, a TV card is a cool gadget to
have on your computer. Besides catching up on news or sports
while using some software, you can also receive
S-Video/Composite/RF signals and perform video/frame capture.
Getting your TV card running under Linux is not very difficult.
However there is a lack of easily available documentation on the
Internet. The standard bttv driver provided with most kernels has
limited support for tuner cards.
This document will focus on getting your TV tuner card working